-LRB- CNN -RRB- -- Lewis Hamilton realistically ca n't win the title but the former world champion hopes to challenge powerhouse Sebastian Vettel at the Korean Grand Prix after posting the fastest practice times Friday .

Hamilton 's time of one minute , 38.673 seconds in the second session in Yeongam was about one-tenth of a second quicker than Vettel , the triple reigning world champion who has captured the last two races in Korea .

`` It 's the first time I can remember that second practice has really gone well for me , '' Mercedes ' Hamilton was quoted as saying by Formula One 's website . `` We have n't changed anything but the day just went smoothly and all the processes with the team worked well . I love this track . ''

Vettel admitted there was `` some room for improvement '' in his Red Bull .

`` It will be close with Mercedes , '' he told Formula One 's website . `` Of course we 're not sure what others were doing with their fuel loads today , but it seems close ahead of tomorrow 's qualifying .

`` I like the track here , it 's a shame it 's so far from Seoul , which is a great city , but it 's good coming here as it 's quieter than some other races , which means we can focus on our job . ''

The only driver with half-a-chance of catching Vettel , Fernando Alonso , was a distant seventh in the second session .

He trails Vettel by 60 points with a mere six races remaining and admitted this week he needed a comeback similar to Oracle Team USA 's in the America 's Cup sailing to overtake the German .

But Alonso did n't sound optimistic Friday .

`` There is every probability that , again here , we can expect to struggle in the race , '' Ferrari 's Alonso told Formula One 's website .

`` It wo n't be easy for us in performance terms , but we know that apart from that , we can do well on Sunday . Now , we must try and get the most out of what we have available and put everything together tomorrow and in the race . ''

Kimi Raikkonen , Alonso 's teammate next season , crashed in the first practice session but was unhurt .

Autosport.com quoted the Finn as saying he would take action at the end of the season to fix a lingering back problem .

`` It is not really surgery , but for sure we are probably going to do something , '' said Raikkonen . `` I know what the issues are . ''

@highlight

Lewis Hamilton posts the fastest practice times ahead of the Korean Grand Prix

@highlight

Sebastian Vettel was about one-tenth of a second slower than Hamilton in the second session

@highlight

Vettel has won the last two races in Korea and is on course for a fourth world title in a row

@highlight

Fernando Alonso , second in the individual standings , came seventh in the second session